CAREER: Entropy-driven oxynitrides

NON-TECHNICAL SUMMARY: This award supports research to create new inorganic materials that function as visible-light-activated photocatalysts that promote national resiliency through the generation of value-added products. Because these novel inorganic materials contain multiple elements, this research seeks to understand the contributing roles of each constituent in order to better design materials with useful and tunable functional properties. Traditional and synthetic approaches are being utilized to make really tough and exceptionally strong ceramic materials that owe much of their strength to their unique atomic structure which is characterized by oxygen atoms and nitrogen atoms replacing, switching or mixing with one another. When scientists take advantage of these irregularities in the crystal structure to either encourage or discourage these types of atomic switching, these inorganic ceramic materials are called “entropy-driven oxynitrides”. This project is systematically adjusting positively charged ions (cation) and negatively charged ions (anions) in these oxynitrides to realize their impact on properties. Furthermore, because these materials are extremely underexplored, this research is mapping the ways in which entropy-driven oxynitrides form through studies that uncover the influence of starting materials and reaction conditions on the final products. Awareness of reaction pathways to these materials accelerates their development and reduces waste to scale-up. This award also supports activities to expose a broad age range of students to functional inorganic materials science through low-cost, hands-on science kits (grades K-12) and focused research experiences and in-class learning related to materials for resiliency topics for both undergraduate and graduate students at Drexel University. TECHNICAL SUMMARY: Entropy is a key driving force for achieving stable solid solutions containing multiple elements. High entropy oxides are one example in which multiple cations, often five or more, homogeneously and randomly occupy cation lattice sites in their structures. From the anion side, incorporation of nitrogen into oxide structures results in tailorable electronic and optical properties. This award supports research focused on understanding what further synergies lie in inorganic materials with multiple anions and cations and how the contributing roles of each constituent can be better understood. Specifically, this research is leveraging cation and anion choice in designing entropy-driven oxynitride materials with tunable morphologies and functional properties, which are relevant for their application in visible-light-activated photocatalytic reactions such as water oxidation, methane oxidation, and photodegradation of anthropogenic pollutants. The central hypothesis is that cation and anion choice are more influential on properties than sheer number of constituents. Traditional solid state and nascent infiltration approaches are being developed to synthesize the entropy-driven oxynitrides, and cation number and choice are being systematically varied to realize their contributions to the physical, chemical, and functional properties. Reaction pathways to these underexplored materials are also being elucidated through in situ synthetic studies to uncover the roles of precursors, intermediates, and reaction conditions on product formation. This award also supports educational and outreach activities that are informed by the research direction, including incorporating new inquiry-based science activities on functional inorganic materials into low-cost kits for K-12 students and involving undergraduate and graduate students in science through research and course participation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2540777 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT,01003031DB NSF RESEARCH & RELATED ACTIVIT,01002930DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Jill Wenderott | Institution: Drexel University, PHILADELPHIA, PA | Award Amount: $390,113 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2540777 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2540777.html